In vitro cytotoxicity of dental adhesive systems under simulated pulpal pressure.
OBJECTIVE
Most of the devices used to evaluate the cytotoxicity of resin-based composites in vitro use a dentin barrier test. However, it is difficult to obtain the number of freshly extracted teeth, all on the same day, that is necessary for powerful statistical analysis. Tooth cryopreservation provides a way to build up a supply of teeth. This in vitro study compared cryopreserved teeth and freshly extracted teeth in an evaluation of the cytotoxicity of resin-based composites. In addition, this study also evaluated the effects of pulsatile pressure and the importance of dentin permeability on the cytotoxic response to bonding resins.


METHODS
Forty freshly extracted and forty cryopreserved third molars were used. A standardized Class I cavity was prepared within the dentin. The hydraulic conductance of each tooth was recorded. The cavities were filled either with Scotchbond Multi-Purpose Plus and Z 100 (3M Dental Products) or with Optibond and Herculite (Kerr). A plexiglas device was designed to permit 24 h long contact between culture medium and the roof of the pulp chamber while a pulsatile pulpal pressure was simulated. The viability of L 929 cells cultured with a control medium and evaluated by an MTT assay was compared to that of L 929 cells cultured with medium which remained for 24 h in contact with the pulp chamber of restored teeth. A three-way ANOVA was used to compare the cytotoxicity among the different groups. A simple least-squares linear regression was used to seek a relationship between the hydraulic conductance of dentin and the cytotoxicity of composite restorative materials.


RESULTS
No significant differences in cytotoxicity were found between the freshly extracted teeth and the cryopreserved teeth (p = 0.53). The cytotoxicity of the resin adhesives was statistically higher when a pulsatile pulpal pressure was simulated (p = 0.04). A significant relationship was found between the hydraulic conductance of dentin and the cytotoxicity of resin-based composites (p = 0.02).


CONCLUSIONS
Cryopreserved teeth can be used for in vitro evaluation of the cytotoxicity of resin adhesives. Pulsatile pulpal pressure simulations increased the in vitro cytotoxicity of the tested materials.
Camps
J
J
Unité IMEB, Faculté d'Odontologie, Marseille, France. Jcamps2035@aol.com
Tardieu
C
C
Déjou
J
J
Franquin
J C
JC
Ladaique
P
P
Rieu
R
R
D000328:Adult; D000704:Analysis of Variance; D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000633:toxicity; D001794:Blood Pressure; D003188:Composite Resins / Q000633:toxicity; D015925:Cryopreservation; D003782:Dental Pulp / Q000098:blood supply / Q000187:drug effects* / Q000502:physiology; D003804:Dentin / Q000502:physiology; D003806:Dentin Permeability; D017220:Dentin-Bonding Agents / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000187:drug effects; D006801:Humans; D006874:Hydrostatic Pressure; D007739:L Cells / Q000187:drug effects; D016018:Least-Squares Analysis; D008689:Methacrylates / Q000633:toxicity; D051379:Mice; D011673:Pulsatile Flow; D019279:Resin Cements / Q000633:toxicity*; D013997:Time Factors
D003188:Composite Resins; D017220:Dentin-Bonding Agents; D008689:Methacrylates; C088316:Optibond Dual Cure; D019279:Resin Cements; C084018:Scotchbond Multi-Purpose; D017438:Bisphenol A-Glycidyl Methacrylate